Farmers are hitting back at a survey that found Kiwis believe the dairy industry is contributing to degradation of the country's water quality.

Seventy per cent of those who participated in a survey by Horizon Research, funded by Fish & Game, said the expansion of dairy farming had made water quality worse than 20 years ago.

Dunsandel farmer Ron Ferriman said no-one wanted declining water quality, especially those who lived off the land.

"We have to drink the water. Our children and our children's children and our friends and family drink the water."

He said water quality, where it had got worse, was due to several sources.

"I think pointing the finger at one industry is particularly unfair."

Ferriman had adopted several practices aimed at maintaining, and enhancing, the environment on his property including investing in effluent systems.

Federated Farmers Mid-Canterbury provincial president Chris Allen said everyone, himself included, wanted good water quality, with farmers "spending billions" on improving the environment.

"Farmers are not the whole of the problem and they are not all of the solution," he said. "We are working really hard."

He said the national policy statement on fresh water and the national objective framework dealt with many of the respondents' concerns, but it appeared many may not have been aware of them before they commented.

Allen said growth in dairy farming had been spurred by other types of farming, including beef and crops, becoming less profitable.

However, Green Party MP Eugenie Sage said tighter rules needed to placed on expansion, including charges on commercial irrigation, to curtail development and ultimately stop the degradation of water quality.

The survey by Horizon Research was conducted in November.

The survey talked to 3134 people aged 18 or over and has an error margin of +/- 1.8 per cent.